Fuze for non-rotating shaped charge projectiles



April 12, 1955 J. w. MosEMAN, JR 2,705,921

FUZE FOR NoN-ROTATING SHAPED CHARGE PROJECTILES April 12 1955 J. w. MosEMAN, JR 2,705,921

FUzE FOR NoN-ROTATING SHAPED CHARGE PROJECTILES Filed nec. 15, 1949 s sheets-sheet 2 5 rvucfnfo'v E' E] .JmhnMAMnsEmar-Ljn www April 12, 1955 J. w. Mosr-:MAN, JR 2,705,921

FUZE FOR NoN-ROTATING SHAPED CHARGE PROJECTILES Filed Dec. 15, 1949 s sheets-sheet s Jahn WME15Eman,Jr.

United States Patent O FUZE FR NON -ROTATING SHAPED CHARGE PROJECTILES John W. Moseman, Jr., Bethesda, Md., assignor to the United States of America as represented by the Secretary of the Army Application December 15, 1949, Serial No. 133,201

2 Claims. (Cl. 10278) (Granted under Title 35, U. S. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment to me of any royalty thereon.

This invention relates to fuzes for projectiles having shaped charges, more particularly to projectiles of the non-rotating type such as those fired from a mortar or rocket.

The great armor-penetrating power of the jet from a shaped charge when detonated at the proper stand-off distance and without substantial obstruction between the jet and target, is well known. In prior art practice, it was common to employ an inertia-operated fuze located in the base of the projectile. Since the maximum effectiveness of the shaped charge depends upon detonation at a critical stand-off distance from the target, and also since inertia-operated fuzes require an appreciable time for action, a relatively heavy nose cap or windshield was required in order to slow down the projectile on impact, in order to give the firing pin time to act, it being understood that the times referred to are measured in millionths of a second. However, the heavy nose cap was undesirable for shaped charge projectiles because it interposed a serious obstruction between the charge and the target and thus tended to reduce the maximum effectiveness and penetration of the jet. Even when a percussion primer was used in the nose cap of the projectile, a relatively heavy cap was required to provide attaching threads and a firm mounting for the primer. Furthermore, such types of fuzes usually add an item of time and expense in that a special protective cover is required for the otherwise exposed primer, which cover must be removed and discarded prior to ring.

It is therefore an object of my invention to provide a fuze for shaped charge projectiles of the non-rotating type in which the above-mentioned disadvantages are obviated.

It is a further object to provide a fuze for use with shaped charge projectiles of the non-rotating type, which is rapid and reliable in action and which detonates at the optimum predetermined stand-off distance from the target.

Another object is to provide a fuze of the type mentioned in which a unitary fuze body carries all of the operating parts and is easily shattered on impact.

Still another object is to provide a fuze which has a graze action and therefore is self-destructive in case it misses the target.

Other objects and advantages will become apparent after a study of the following description in connection with the drawings wherein:

Fig. l is an elevation, to a reduced scale, of the nose portion of a projectile equipped with the fuze forming the subject of the invention.

Fig. 2 is a longitudinal axial section of the fuze and forward portion of the projectile, taken in a plane identified by the line 2 2 of Fig. l with the fuze unarmed.

Fig. 3 is a cross section on line 3 3, Fig. 2, the fuze being unarmed.

Fig. 4 is a cross section in the same plane as Fig. 3, but showing the fuze armed.

Fig. 5 is a longitudinal section taken in planes indicated by the line 5 5, Fig. 3 showing the graze-action firing mechanism.

Fig. 6 is a longitudinal section taken on line 6 6, Fig. 3 to show the connection between the graze-action tiring mechanism and auxiliary detonator.

2,705,921 Patented Apr. 12, 1955 Fig. 7 is a cross section in a plane identiiied by line 7 7, Fig. 2.

Fig. 8 is a detail cross section on line 8 8, Fig. 5 showing the safety wire in position.

Fig. 9 is a longitudinal axial section of a modified form of fuze in unarmed condition.

Fig. l0 is a cross section taken in a plane identified by the line 10 10 of Fig. 9, and

Fig. 11 is a longitudinal cross section taken in a plane as indicated by line 11 11, Fig. 9.

Referring in detail to the drawings, the numeral 1 identifies a one-piece fuze body, which may be a casting of aluminum alloy having relatively thin walls. A generally semi-circular channel 2 is formed in the rear face of the body to define a central portion 1b and a skirt portion 1a, threaded into the forward end of a projectile casing C having therein a shaped charge S with liner L. It will be understood that the charge C has a lined central axial passageway leading to a booster pellet at the base of the charge.

The front end of the fuze body has a forward extension 1c formed with a central axial bore 3. The tip of extension 1c is counterbored to form a seat for a pinless or impact primer 4, held in place by crimping or staking, as indicated at 5. The rear portion of bore 3 is enlarged as at 3a for the accommodation of an auxiliary detonator -6. As clearly shown upon Figs. 2 and 6, this detonator consists of a one-piece cup 6a having its closed rear end formed in the shape of a re-entrant cone. A holder or collar 7 is threaded into the enlarged rear end of counterbore 3a and has an inward ange 7a engaging over the end of the detonator cup, to hold the same on its seat formed between the bore and counterbore. A thin disk 8 resting on the aforesaid seat, closes the forward end of the detonator.

The bore 3 is intersected at its rearward end by a transverse cylindrical passage 9 having therein a slider 10 slidable in the passage from the safe. position shown in Pigs. 2 and 3, to a second armed position shown in Fig. 4, wherein a transverse diametrical hole 11 in the slider, and a second detonator 12 fixed therein, are in alignment with 'oore 3 so that, in the second position, the primer 4, and detonators 12 and 6 are in detonating relation and the fuze is armed. Slider 10 is urged into armed position by a coil spring 13 seated in an axial bore 14 in the end of the slider. This spring acts between the bottom of the bore and a dished disk 15 secured in place over the otherwise open end of passage 9, as by staking.

Means which acts at one and the same time to prevent rotation of the slider in its bore or passage, and to hold it in armed position once it is move-d to such position, are shown at Figs. 3 and 4. An axially-extending groove or channel 16 formed in slider 10, has a progressively decreasing depth from its forward end and terminates in a hole 17. A locking pin 1S has rounded ends and an enlarged central portion slidably fitting a hole in fuze body 1 and opening into passage 9. A spring 19 iits around one end portion of the locking pin and acts between its enlarged portion and a plug 20 to urge the other end of the pin into groove 16. As will be obvious from Figs. 3 and 4, as the slider moves toward armed position, the bottom of groove 16 cams pin 13 outwardly against the urge of spring 19, until, as the slider moves into fully armed position, the end of the pin snaps into hole 17 and thereby prevents return movement of the slide to unarmed position. In addition, the construction just described prevents rotation of slider 10 within its bore 9 and thus assures that bores 11 and 3 are properly aligned when the slider is moved to armed position.

Movement of slider 10 to armed position is normally prevented by a bore-riding safety pin 21 extending through holes 1e and 10b in body 1 and slider 10 respectively, which holes are aligned when the slider is in the unarmed position of Figs. 2 and 3. The pin has a head 21a, Fig. 3, whose outer surface is normally coincident with the adjacent external surface of the fuze body. From Fig. 2, it will be noted that the axis of the pin, when in operative position, extends diametrically across the central axis of the fuze, at an acute angle to the axis of passage 9 and slider 10. The pin is urged outwardly, that is, toward a position freeing slider 10, by means of a spring 22 located in a counterbore in body 1, and engaging at its respective ends against the end of the counterbore and head 21a. As shown, the end of the spring is secured to the pin, as by having one end contracted into a groove contiguous to head 21a.

Safety pin 21 is held in the position shown at Fig. 3, against the outward urge of spring 22, by a set-back pin or element 23 (see Fig. 5) mounted for sliding movement in a hole 24 bored axially forwardly from channel 2 and having its forward end 23a engaging a transverse bore 25 in the forward end of safety pin 21, to thereby prevent withdrawal of the safety pin, as clearly shown upon Fig. 5. From this figure, it will be noted that pin 23 is formed with an integral spool 23b intermediate its ends and which, inter alia, serves as an abutment for one end of a light coil spring 26, surrounding the adjacent end of pin 23. Spring 26 at its other, or rearward end, abuts a plug 27 threaded into the enlarged end of bore 24 and having a central aperture within which pin 23 has a smooth guided t. Spring 26 thus acts to urge pin 23 into the position shown upon Fig. 5, with its forward end in hole 25 preventing withdrawal of safety pin 21. Since the axis of element 23 is parallel with the longitudinal axis of the fuze, with end 23a forwardly, firing of the projectile to which the fuze is attached causes set back against the action of spring 26. Pin 23 is thereby moved out of hole 25, releasing safety pin'21 to the action of its spring 22. During its passage along the gun barrel, head 21a of pin 21 will ride the bore. On emergence from the barrel, safety pin 21 will be forced outwardly by spring 22 to release slider 10. The latter then moves to armed position under urge of its spring 13 and is held in this position by the action of locking pin 18, as previously described.

A thin-wall ogival nose or windshield 28 is secured to the fuze body as by crimping its base into a circumferential groove in the body, as indicated at 29, Fig. 2. It will be noted that the tip of windshield 28 lies closely adjacent primer 4 so that the latter is initiated instantly on impact. The windshield, being of thin metal, is easily crushed and disintegrates on impact, but affords adequate protection to the fuze prior to ring. From Fig. 3, it will be noted that the windshield has a hole 28a positioned to permit insertion of pin 21. The head 21a lies ilush with the outer surface of the windshield and is slotted parallel with hole 25. From Fig. 3 it is noted that the end of pin 21 is pointed so that when the pin is inserted, it will cam set-back pin 23 inwardly until the latter is forced into hole 25 by its spring 26.

A safety wire 30 is generally in the form of a helix extending a little more than 180 about the nose cap and having a straight chordal end 30a, Fig. 8, adapted to be inserted through aligned holes in the nose cap and fuze body, to pass within the confines of spool 23b and thus prevent accidental withdrawal of pin 23 from hole 25 in safety pin 21, as is clear from Figs. 5 and 8.

In order to provide for self-destruction of the projectile in case it misses the target, the fuze is equipped with tiring means responsive to a grazing of the projectile against an object. For this purpose the fuze body is formed with a bore 31, Figs. 3 to 6, opening through the front face thereof and having its axis parallel to and offset from the axis 32 of the fuze body. From Figs. 3 and 4 it is noted that the axis of bore 31 is offset from, but intersects at right angles, the bore 9 of slider 10. A plunger 33 is slidably mounted in bore 31 and is normally urged rearwardly against the bottom of bore 31,

. by a light spring 34 seated at one end in a depression in plunger 33 and at the other end in a depression in the face of a plug 35 threaded into the enlarged open end of bore 31. The plunger has a central bore 36 opening rearwardly into an enlarged chamber in which a primer 37 is fixed. A firing pin 38 has its head secured to plug 35 as by staking and extends through spring 34 rearwardly into bore 36. The relations and dimensions are such that when plunger 33 slides forwardly into engagement with plug 35, pin 38 strikes primer 37 and detonates 1t.

Plunger 33 has a portion of its forward end cut away as at 33a to conform to the cylindrical surface of bore 9 and to leave the bore unobstructed. Normally, that is, in its unarmed position, slider fits within the cutout in plunger 33 and thus positively prevents forward movement of the latter as is clear from inspection of Fig. 6. However, slider 10 has a peripheral cut-out 10a, Figs. 3 and 4, of the same radius as bore 31 and so located that, when the slider moves into armed position its cut-out conforms to the walls of bore 31 and frees plunger 33 for forward movement in response to slight retardation of the projectile such as that produced by a grazing action which might not be suicient to initiate primer 4. From Fig. 6, it will be noted that a ash passage 39 leads from the rear of bore 31, to the corresponding end of counterbore 3a and auxiliary detonator 6 so that the ash from primer 37 initiates detonator 6 and thereby the main charge.

The operation of the fuze will be clear from the foregoing description. Prior to firing, safety wire 30 is removed, thus freeing pin 23 for movement. When the projectile is fired, the inertia of pin 23 causes its end to move out of hole 2S in the end of pin 21 and, as soon as the projectile leaves the gun barrel, pin 21 is forced out of the fuze by spring 22. Spring 13 then forces slider 10 to the armed position of Fig. 4 where it is locked by pin 18, with detonator 12 aligned with axial bore 3. On impact with a target, primer 4 is instantaneously initiated and in turn, initiates detonators 12 and 6. The latter directs a powerful jet axially and rearwardly to initiate the booster pellet, not shown, at the base of charge S to thereby detonate the charge. The fuze action is extremely rapid so that the shaped charge is detonated at the stand-olf distance necessary for maximum penetration of the target by the resulting jet. The thin nose cap 28 and aluminum alloy body 1 are readily disintegrated by the impact and thus offer minimum obstruction to the jet. The effectiveness of the jet is increased by the fact that the projectile, being fired from a mortar or launcher, does not rotate or spin.

In Figs. 9 to ll, there is shown a modified form of the fuze just disclosed in which a fuze body 40 has an externally threaded skirt 40a by which it is attached to projectile casing C. A central longitudinal passage 41 in body 40 extends forwardly through extension 4017, and terminates rearwardly in an enlarged threaded counterbore 42. A transverse bore 43 intersects passage 40 intermediate the ends thereof. A slider 44 fits the bore 43 and is mounted therein for translation from the unarmed position of Fig. 9, to an armed position, not shown, wherein a diametral hole 46 in the slider, is aligned with passage 41. A detonator 45 is secured in hole 46. Slider 44 is urged into armed position by a spring 47 engaging the base of the slider at one end and an abutment 48 at the other, here shown in the form of a cap threaded into the enlarged end of bore 43. A pinless primer 49 is mounted in the forward end of extension 40b. An auxiliary detonator 50 is threaded into counterbore 42. This detonator may be substantially the same in construction and operation as detonator 6, described in connection with the species of Figs. l to 8. Hence it is sufficient to identify holder 50a, cup 50b conically shaped at its rearward end and flanged at its forward end to be clamped in position by the holder. In its unarmed position, slider 44 cuts olf primer 49 from detonator 50. Furthermore, at this time, detonator 45 is confined within bore 43. The fuze is thereby rendered safe.

Slider 44 is held in safe position by a safety pin 51 which normally seats in a bore 52 normal to the central axis of the fuze and to bore 43 and intersecting the latter. Slider 44 has a slot or aperture 53, the end of which is aligned with bore 52 when the slider is in unarmed position whereby the slider is positively held in such position, as long as the pin is in normal position.

Pin 51 is urged outwardly by a spring 54 surrounding the pin and seated in the enlarged outer end of bore 52. The spring is secured to the pin adjacent the head thereof, by a constriction seated in a channel in the pin contiguous to its head 51a. Normally, pin 51 is held in the position shown, by a set-back element 55, Fig. ll, having a reduced end fitting a transverse hole 56 in the end of the pin. Element 55 is urged forwardly into the position shown, by a spring 57 within a bore in body 40 and held under compression by a plug 58.

In order to prevent rotation of slider 44 within its bore, and to lock the slider in armed position once it has been moved to such position by spring 47, the slider has a longitudinal channel or groove 59 of progressively decreasing depth frorn the inner end thereof. A locking pin 60 is slidable within a bore in body 40 and projects into bore 43 in position to ride in channel 59 as the slider moves toward armed position. The locking pin is urged into the position shown by a spring 61 engaging the enlarged central portion of the pin. This portion also acts to limit the penetration of the pin into bore 43. Spring 61 is held under compression by a plug 62 threaded into the enlarged end of the bore, in which element 60 is slidable. A hole 63 in slider 44, opens into the bottom of channel 59 and is so positioned that the end of pin 60 snaps into the hole at the instant the slider moves into armed position, to thereby lock the fuze in armed condition. Normally safety pin 51 acts to prevent rotation of slider 44 within its bore and as soon as the pin is withdrawn the slider immediately moves to position its groove over pin 60 so that, this pin prevents rotation of the slider during its movement to armed position and assures that, in the final fully armed position, detonator 45 is aligned with passage 41.

A nose cap 64 of thin metal is shown as enclosing the fuze and secured to the fuze body by crimping as at 64a. When the fuze is screwed into the projectile preparatory to firing, the crimped portion of the cap is clamped within the joint. It will be noted that the tip or forward portion of cap or windshield 64, is closely adjacent primer 49 so that initiation of the primer is substantially instantaneous after impact. From Figs. and 11 it will be noted that a hole 65 is provided in windshield 64 to permit the insertion of pin 51. A safety Wire 66, Fig. 11, may pass through aligned holes in the fuze body and element 55 to hold the latter in the position shown until the wire is withdrawn.

The operation will be clear from the foregoing description. When the projectile equipped with one of the improved fuzes is fired, the inertia of element 55 results in its rearward movement out of the hole in safety pin 51. On release of the pin, its spring 54 forces it outwardly and as soon as the projectile leaves the gun barrel, the pin is forced out of the fuze. As soon as pin 51 moves out of slot 53, spring 47 forces the slider toward armed position with pin 60 riding in channel 59 and being gradually cammed inwardly by the decreasing depth of the channel. As detonator 45 moves into alignment with passage 41, pin 60 snaps into hole 63 and locks the slider in armed position. On impact with the target, windshield 64 is crushed and primer 49 is initiated to, in turn, initiate detonators 45 and 50. The latter, operating upon the shaped charge principle, or Munroe effect, projects a ame jet axially along the projectile to detonate the booster pellet at the base of the charge and thereby the main charge. The action is substantially instantaneous so that a thin light nose cap is suiiicient. As in the species of Figs. 1 to 8, body 40 may be a relatively thin-walled casting of aluminum alloy so that it disintegrates on impact and oers minimum obstruction to the jet from the main charge.

While I have disclosed a preferred species and a modified form, various changes, substitutions and modications will occur to those skilled in the art after a study of the disclosure. Therefore, I wish to have the disclosure taken in an illustrative rather than a limiting sense, for it is my desire and intention to reserve all modifications falling within the scope of the subjoined claims.

In the claims, the term axis or central axis of the fuze means the axis thereof coincident with the longitudinal axis of the attached projectile which, in Fig. 9, is coincident with line 11-11.

Having now fully disclosed the invention, what I claim and desire to secure by Letters Patent is:

1. In a fuze, a fuze body having a dash passage,

a slider movable to open and close said passage, a safety pin holding said slider in passage-closing position, means urging said slider to passage-opening position, means urging said safety pin to release said slider, and means engaging and maintaining said pin in slider-holder position and movable in response to set-back forces to release said pin, a pinless primer and first detonator in respectively front and rear ends of said passage and on opposite sides of said slider, a second detonator carried by said slider and moved into said passage in response to movement of said slider to passage-opening position, an inertia plunger mounted in a bore in said fuze body, auxiliary detonating means, means rendered effective by movement of said plunger to initiate said auxiliary detonating means, said slider when in passage-closing position engaging and holding said plunger against movement and when 1n passage-opening position freeing said plunger for movement, there being a ash passageway from said bore to said iirst detonator.

2. In a point initiating fuze for a non-rotating projectlle, a generally cylindrical, one-piece body of lightweight disintegrative metal having a reduced forward extension coaxial of its central longitudinal axis and also having a central axial first bore through said body and extension, a primer and a detonator fixed in and closing the forward and rearward ends, respectively, of said first bore, there being a transverse passage in said body intersecting said first bore between said primer and detonator, a slider slidably fitting said passage and translatable therein from a first position closing said bore, to a second position leaving the same unobstructed, there being holes in said body and slider aligned only when said slider is in first position, a bore-riding pin fitting said aligned holes to retain said slider in first position, spring means in said body urging said slider into second position, spring means in said body urging said pin out of said body, a set-back pin fitting aligned holes in said body and bore-riding pin, there being a second bore in said body parallel with and radially offset from said first bore and intersecting said passage in offset relation therewith, a plunger slidably fitting said second bore for movement in response to deceleration from a rearward to a forward position, said slider when in first position only, engaging said plunger to prevent forward motion of the same, and when in second position releasing said plunger for forward motion, a second primer carried by said plunger, means iixedin said body and responsive to forward movement of said plunger to second position to initiate said second primer, there being a second passage connecting the rearward end of said second bore and said detonator, said second primer being in communication with said second passage only when said plunger is in forward position.

References Cited in the file of this patent UNITED STATES PATENTS 1,375,466 Ragsdale Apr. 19, 1921 1,933,608 Teitscheid Nov. 7, 1933 2,118,062 Woodberry May 24, 1938 2,336,514 Teitscheid Dec. 14, 1943 FOREIGN PATENTS 404,549 Great Britain Jan. 18, 1934 577,531 Great Britain May 22, 1946 

